Pascal


var a,b: array[1..100] of string;
    i,j,k,n: integer;
    s: string;
    f: boolean;
begin
readln(n);
for i:=1 to n do
 begin
 readln(s);
 f:=false;
 for j:=1 to n do
  if a[j] = s then f:=true;
 if f = false then a[i]:=s
 else begin
      f:=false;
      for j:=1 to n div 2 do
       if b[j] = s then f:=true;
      if f = false then b[i]:=s;
      end;
 end;
for i:=1 to n div 2 do
 if b[i] <> '' then writeln(b[i]);

end.